*\cMore ROTATE spawnflag

These 3 func_trains each have the ROTATE spawnflag set, and pitch_speed = yaw_speed =
constant. The path_corners do not change either the pitch or yaw speeds.

To prevent rotation around an axis when there is a corresponding angle change between
path_corners, set the corresponding rotational speed to 0. For example, you could prevent
these crates from pitching up/down by setting pitch_speed = 0.

To prevent ANY rotation from one path_corner to the next, set the NO_ROTATE spawnflag for
the destination path_corner.

The crate func_trains use the SMOOTH_MOVE spawnflag. Without SMOOTH_MOVE you'd notice a
slight pause at most of the path_corners. You do NOT want to use SMOOTH_MOVE if exact
func_train placement is critical.